Optical bistability is a phenomenon in which a nonlinear optical medium, exhibiting an index of refraction depending on the intensity of incident light, responds to an optical input beam by changing its light transmission from one value to another.
As described in Optical Bistability: controlling Light By Light (Academic Press, New York, 1985) by H. M. Gibbs, a device is optically bistable if two stable output states exist for the same value of the input over some range of imput values. Thus, the intensity transmitted through a bistable device can be plotted as a function of incident intensity. For each cycle of the incident intensity I.sub.in, the transmission of the device remains low until I.sub.in is increased beyond some critical value I.uparw.. The transmission then remains high even as I.sub.in is decreased until another critical value I.uparw. (&lt;I.uparw.) is reached and the device switches to the off state. This type of hysteresis effect is a fundamental characteristics of optical bistability.
IEEE Spectrum, 18, 26 (1981) by P. W. Smith et al identifies four features which are important characteristics of bistable optical devices. These include a bandwidth greater than 10.sup.13 Hz; a switching time between about 10.sup.-9 -10.sup.-12 second; a capability for parallel processing; and the ability to process light directly.
Optical bistability and optical nonlinearity and related effects which are pertinent with respect to the present invention are described in publications which include Optics Commun., 19 (No. 1), 138 (1976) by M. Okuda et al; J. Chem. Soc. Faraday Trans. 2, 74, 1870 (1978) by J. McVie et al; Appl. Phys. Lett., 33(1), 24 (1978) by P. W. Smith et al; Optical Engineering, 24 (No. 1), 68(1985) by N. Peyghambarian et al; and U.S. Pat. Nos. 3,610,731; 3,745,476; 3,790,252; 4,012,699; 4,515,429; 4,558,923; and 3,813,605.
Because of its extraordinary range of optical signal processing capabilities, a bistable optical device has potential as a key component in a number of optical systems which include high-speed optical communications repeaters and terminal equipment, data communication networks, and systems for the direct optical processing of visual images.
There is increasing interest in the development of improved optical-signal processing systems using all-optical circuitry, deriving from recent advances in long-lived light sources, high quantum efficiency detectors, and low-loss high-bandwidth optical fibers.
Accordingly, it is an object of this invention to provide a bistable optical device in which the index of refraction of a intracavity medium depends on the light intensity.
It is another object of this invention to provide a bistable optical device consisting of Fabry-Perot etalon containing an organic nonlinear optical component.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.